Foam inhibition of oils



United States Patent FOAM INHIBITION OF OILS Dilworth T. Rogers, Summit, and John P. McDerinott,

No Drawing. Application March 28, 1955, Serial No. 497,438

13 Claims. (Cl. 252-33) The present invention relates to the foam inhibition of oils and particularly to the prevention of foaming and frothing in organic compositions such as hydrocarbon oils and related material which contain additives tending normally to promote foaming. The invention is applicable particularly to lubricating oils containing a detergent additive and the like but it is applicable also to other liquid hydrocarbon oils having a viscosity ranging between that of kerosene up to very heavy visccsities which are characteristic of the most viscous lubricating oils.

The present application is a continuation-in-part of Serial No. 239,852, filed August 1, 1951, now abandoned.

As is well known in the prior art, lubricating oils, hydraulic oils and the like which foam excessively frequently cause operating difiiculties in machinery as well as in the processing of the oils themselves. Various materials have been proposed in the past for adding to such oils to inhibit their foaming. In recent years there has been a marked trend toward the use of detergent additives,

particularly in lubricating oils .and hydraulic oils, and to 0 a lesser extent in fuel oils. These additive materials, which are desirable because they prevent sludging, depo sition of gum and the like, are strong foam promoters and the modern tendency to use such materials in increasing quantities gives rise to increasing difiiculties with foammg. I

It has been proposed in the past to inhibit foaming of organic compositions by adding minor proportions of various materials including fluorinated hydrocarbons, long chain alcohols, and small quantities of silicone polymers having foam suppressing characteristics. The action of these anti-foamants appears to be quite specific and their activity cannot, in general, be predicted. Anti-foaming activity appears to have some relation to oil-insolubility as well as to surface tension but the factors which determine Whether a given oil composition will foam are not clearly understood.

In general, the heavier the hydrocarbon oil and the greater its content of detergent additive, the greater will be its tendency to foam and the more diificult to inhibit its foaming. 'Dhe foaming tendency, however, varies also with the particular type of oil and varies even more with the particular type of detergent, or other foam promoting additive. The fatty acid soaps of most metals, the 011 soluble sulfonates, various aliphatic esters and amines and the salts of alkylated aromatic compounds such as alkyl phenol sulfides, alkyl phenolates, the phosphorus sulfide treated derivatives of such materials and the like, frequently tend to promote foaming in conventional mineral base hydrocarbon oils. The degree of foaming in each case varies with the particular constituents and the type and degree of agitation to which the oil is sub ected.

In general, prior art attempts to prevent foamingof oils have been based upon the addition of certain anti-foaming materials to the oil compositions. One feature of the present invention resides in the discovery that a pretreatment of the foam promoting additive can greatly reduce the foaming tendency of oil containing the additive.

According to the present invention additives of the above types, especially the widely used detergents such as the alkaline earth metal, or other metal salts of alkylated phenols, alkylated phenol sulfides and their phosphorus sulfide derivatives, sulfonates and mixtures thereof, are treated preferably in oil solution with about 0.1 to 50%, and preferably about 1 to 30% by weight, based on the dry additive, of a saturated or unsaturated short chain aliphatic alcohol containing from 1 to 5 carbon atoms. The saturated alcohols are preferred.

Thus detergent additives may be treated'with methyl, ethyl, propyl, or butyl alcohol, or one of the other lower aliphatic alcohols or mixtures thereof. For eifective foam inhibition the alcohol treating agent must not be substantially oil soluble and this precludes the use of higher alcohols. The alcohol treatment is preferably supplemented, in some cases at least, by adding an inhibitor such as diamyldiethoxy silane in small proportions.

The method of the present invention is particularly effective in reducing the foam-promoting tendencies of metal sulfonates, metal alkyl phenol sulfides, phosphosulfurized metal alkyl phenol sulfides and mixtures thereof. These particular compounds are Well known to the art as detergent additives for lubricating oils, particularly mineral lubricating oils. They are generally employed in the form of alkaline earth metal salts (the sulfonates are frequently also employed in the form of alkali metal salts also). The metal sulfonates and their preparation are described in detail, for example, in U. S. 2,467,176; the metal alkyl phenol sulfides and their preparation are described in detail, for example, in U. S. 2,362,289; the phosphosulfurized metal alkyl phenol sulfides and their preparation are described in detail, for example, in U. S. 2,451,345. Specific examples of these detergent additives include:

Barium tert. octyl phenol sulfide Calcium tert. octyl phenol sulfide Barium-calcium tert. octyl phenol sulfide Barium tert. amyl phenol sulfide Calcium tert. amyl phenol sulfide Barium-calcium tert. amyl phenol sulfide Barium nonyl phenol sulfide Oalcium nonyl phenol sulfide P285 treated barium tert. octyl phenol sulfide P255 treated calcium tert. amyl phenol sulfide P285 treated barium-calcium nonyl phenol sulfide Calcium petroleum sulfonate Barium petroleum sulfonate Sodium petroleum sulfonate Calcium Ca alkyl benzene sulfonate Barium C9 alkyl benzene sulfonate Sodium C16 alkyl benzene sulfonate Mixtures of such metal sulfonates with metal alkyl phenol sulfides and/ or phosphosulfurized metal alkyl phenol sulfides in proportions of about 5 to by weight, preferably about 10 to 50% by weight, of the metal sulfonate, are employed frequently in lubricating oil compositions.

The treatment of the foam-promoting detergent additives with alcohol in accordance with this invention is preferably carried out with the additives in the form of additive concentrates. Generally these additive concentrates will contain about 10 to 70% by weight of the dry additive and preferably about 25 to 50 wt. percent of the dry additive. The remainder of the additive will be pre dominantly a diluent oil in which the detergent additives are soluble, preferably a mineral lubricating oil. In certain instances the additive concentrate may contain minor proportions of other additives such as anti-oxidants, viscosity index improvers, and the like. The alcohol is added to the additive in oil solution and the resultant blend blown with an inert gas, preferably nitrogen, at an elevated temperature of about 80 to 170 C. until essentially all of the alcohol has been removed therefrom. This nitrogen blowing may be carried out for about 0.1 to hours and preferably for about 0.2 to 1 hour. Generally at these elevated temperatures essentially all of the alcohol will be removed after about 15 minutes. Lower temperatures will generally require longer treating times. Stirring of the reaction mixture during this treating operation is desirable to provide efiicient contact between the alcohol and detergent additive. The treatment of the detergent additives in the form of an additive concentrate is preferred because there is an efficient contacting between the detergent additives and the alcohol.

A number of experiments were conducted to show the effect of pretreating detergent additives of various types, which detergents were to be added to mineral lubricating oils of SAE 30 grade in concentrations of 5% for a standard foaming test.

In general in these experiments the additive in the form of an additive concentrate and the treating agent were stirred together and heated at about 80 C.l70 C. with continued rapid stirring, accompanied by blowing with nitrogen. The treating temperature depends of course upon the treating agent used, as indicated in the data below.

When the lower aliphatic alcohols are used, the treated additive is preferably heated for some time and blown with nitrogen to evaporate the alcohol. While it appears that some of the conventional detergent additives are less susceptible to this treatment than others, the sulfonates, metal alkyl phenol sulfides and particularly the phosphorus sulfide treated phenol sulfide derivatives, some of which have been mentioned above, are found to be quite susceptible to treatment by methyl and ethyl alcohol as indicated in the following table. The data are based on the standard ASTM Foam Test D89246T. The detergent additive B was an additive concentrate consisting essentially of (1) about 62.5% by weight of a mineral oil (lubricating viscosity) solution containing as the active ingredient about 40% by weight of phosphosulfurized barium tert. octyl phenol sulfide and (2) about 37.5 by weight of a mineral oil (lubricating viscosity) solution containing as the active ingredient about 30% by weight of calcium petroleum sulfonates. The phosphosulfurized barium tert. octyl phenol sulfide was prepared by adding about 4 parts by weight of Pass to about 100 parts by weight of an oil solution containing about 40% by weight of barium tert. octyl phenol sulfide at about 150 C. over a period of about 0.5 hour, soaking the reaction mixture for about 2 hours at about 150 C., blowing the reaction mixture at about 150 C. with N2 for 2 hours, filtering, cooling the reaction mixture to about 60 C. and air blowing the reaction mixture for about 8 hours. Detergent additive C was an additive concentrate consisting essentially of (1) about 62.5% by weight of a mineral oil (lubricating viscosity) solution containing as the active ingredient about 40% by weight of barium tert. octyl phenol sulfide and (2) about 37.5% by weight of a mineral oil (lubricating viscosity) solution containing as the active ingredient about 30% by weight of calcium petroleum sulfonates. In Table I below, FT stands for foaming tendency and F8 for foam 4 stability in accordance with the standards of said ASTM Foam Test.

TABLE I Efiect of alcohol treatment (ml. of foam) 75 F. 200 F. 75 F. (Alter 200 F.) Blend FT FS FT FS FT FS SAE 30 Oil+5% B 470 425 110 0 485 430 SAE 30 Olll-5% B (1.0% MeOH Treat- 180 0 85 0 130 0 SAE 30+5% B (1.0% EtOH trea 450 0 30 0 150 0 SAE 30+5% B (10% EtOH treat) 130 0 30 0 150 0 SAE +5% B 520 490 550 0 E 485 SAE 50+5% B (10% EtOH treat 200 0 100 0 50 0 SAE 30 Oil+5% B (10% Isopropanol treat) 125 0 30 0 110 0 SAE 30 Oi1+5% B (10% n-Butanol treat) 160 0 40 0 210 0 SAE 30 Oi1+5% G 470 410 230 0 465 400 SAE 30 Oil+5% O (10% Methanol treat) 280 0 30 0 35 0 SAE 30 Oil+5% O (10% Ethanol treat 0 20 0 45 0 SAE 30Oil+5% C (10% Isopropan ea 140 0 30 0 0 SAE 30 Oil+5% O (1.0% B

tanol treat) 180 0 35 0 50 0 In the above experiments the additives were treated with alcohol in the proportions indicated, being blown for 45 minutes with stirring and nitrogen blowing at a temperature of C. for methyl alcohol, C. for ethyl alcohol, C. for isopropyl alcohol, and C. for butanol treatment.

As previously indicated, the prior art has shown that it is desirable to add foam inhibiting ingredients, such as alcohols, to oils and related organic materials which give particular trouble in foaming. The effectiveness (in reducing foaming) of alcohol addition is shown below in Table II.

TABLE II Efiect of alcohol addztzon (ml. of foam) 75 F. 200 F. 75 F. (After 200 F.) Blend FT FS FT FS FT FS SAE 30 Oil+5% B 510 270 80 0 450 SAE 80 Oi1+5% B (1.0%

MeOH Treat) 505 50 0 340 40 SAE 30 Oil-{45% B (10% MeOH Treat) 350 10 50 0 200 Trace SAE 30 0il+5% B (10% n-Butanol Treat) 500 290 50 0 460 95 SAE 30 Oi1+5% B (10% n-Butanol Treat) 310 20 50 0 290 10 SAE 30 Oil+5% C 540 470 70 0 420 140 SAE 30 Oil+5% C (1.0%

MeOH Treat) 470 245 80 0 470 105 SAE 30 Oil+5% C (10% MeOH Treat) 445 125 45 0 260 10 SAE 30 Oil+5% O (1.0%

n-Butanol Treat) I. 540 370 80 0 470 160 SAE 30 Oil+5% C (10% n-Butanol Treat) 240 Trace 40 0 Trace It will be noted from the data of Table II that although the addition of alcohol in general reduced foaming, this prior act method was substantially less effective than was the method of this invention (Table I vs. Table II).

Another phase of the present invention is the discovery that diamyldiethoxy silane is an effective additive which may be used alone, with some advantage but has special utility in combination with the alcohol treatment previously described. Proportions from 0.001 up to about 1% by weight, based on the oil composition (not merely on the additive) showed good foam inhibition for the phosphorus sulfide treated alkyl phenol sulfide type detergents. Other dialkyldialkoxy silanes such as dimethyldiethoxy silane, diethyldibutoxy silane, isobutylethyldiethoxy and isobutyl ethyl dibutoxy silane wereconsider- .ably less potent than thediamyldiethoxy ,silane which appears'to have specific activity. The reasons for the differences between these closely related compositions are not TABLE IH Eflect of dialkyldialkoxy silane on foaming A ST M Foam TestD892- 46 T (ml. of foam) 75 F. 200 F. 75 F. (After 200 F.) Blend FT FS FT FS FT FS BAE 30 Oil 200 20 0 145 0 SAE 30 0i1+0.01% Diamyldiethoxysilane 0 0 20 0 0 0 SAE 30 Oil+3% B 440 300 55 0 430 290 SAE 30 Oil+3% B+0.01% Diamyldiethoxysilana 320 20 30 0 300 0 SAE 30 0ii+5% B 470 425 110 0 485 430 SAE 30 Oil+5% B amyldiethoxysilane 300 170 70 0 400 200 SAE 30 Oil+5% B+0.05% Di- 1 amyldiethoxysilane 130 0 80 0 160 0 SAE 30 Oil+5% B+0.01% Dimethyldiethoxysilane 570 520 100 0 565 510 sSAE 30 Oil+5% B+0.01% Diethyldibutoxysilane- 520 440 130 0 535 460 SAE 30 Oi1+5% B+0.01% Isobutylethyldiethoxysiiane- 600 480 100 0 610 475 :SAE 30 Oil+5% B+0.01% Isobutylethyidibutoxysilane..- 500 420 130 0 490 470 .SAE 30 0i1+5% B+0.01% Diisobutyidiethoxysilaue 430 390 130 0 470 360 :SAE +1% 360 300 120 0 425 280 SAE 50 Oil+1% B+0. D

amyldiethoxysilane 40 0 110 0 65 0 For a more universal treatment which will apply to a wider range of additives and oils it is commonly desirable to combine the alcohol treatment with the incorporation of a small amount of diamyldiethoxysilane. In cases where neither of these treatments alone showed marked reduction in foaming, which was particularly noted in the heavy SAE 50 lubricating oils, a combination of the two treatments appeared to have a synergistic efiect. The results are indicated in Table IV.

TABLE IV Effect of combination alcohol treatment plus addition of silanes AST M Foam Test D892-46T (ml. of foam) 75 F. 200 F. 75 F. (After 200 F.) Blend FT FS FT FS FT FS SAE 50 0i1+5% B 520 490 550 O 660 485 SAE 50 Oil+5% B (1% OH s tiggat) 5 7. ..I.; 6 .7. fi1 580 600 470 0 675 490 amyldiethoxysilane 540 500 500 0 510 475 SAE 60 0il+5% B (1% MeOH treat) +0.01% Diarnyldiethoxysilane 150 0 130 0 90 0 SAE 50 Oil+5% B+0.01 Dimethyldiethoxysilane 440 500 500 0 310 220 SAE 50 Oil+5% B (1% MeOH treat) +0.01% Dirnethyldiethoxysilane 470 15 50 0 280 0 1 Additive alcohol treated at 90 C. for 45 minutes with stirring and N blowing.

It will be understood that various combinations of the treatments and ingredients described above may be used and that it may not be necessary to use morethan one of them in compositions where foam inhibition is not too diflicult. As suggested above the heavy lubricating stocks containing fairly high proportions of detergents which are diflicult to inhibitagainst foaming may require both treatments. The invention contemplates the use of either, or both, treatments incombination as may be required for the particular oil stocks and additives in question. I

It will be understood thatthe oil compositions which are subjected to the treatments described above form 'new and useful products, and that the treatments are applicable to fuel oils, hydraulic oils, diesel fuels, gear lubricants, crank case lubricants, and various greases and types of hydrocarbon oil compositions having a viscosity at least as great as that of kerosene. The oil compositions may incorporate various other conventional additives such as anti-oxidants, pour point depressants, corrosion inhibitors, other detergents, film strengthening agents, anti-friction agents, extreme pressure agents, antirust agents and the like as will be apparent to those skilled in the art. While reference has been made in general to the hydrocarbon or mineralbase oils, the invention is applicable also to oils consisting of or containing synthetic oils such as polyesters, e. -g.-di Z-ethyl hexyl sebacate; polyglycols, e. g. the compound formed by condensing butyl alcohol with 14 units of propylene oxide; polyglycol-ethers and the like as well as vegetable and animal oils so far as the same problems of foaming and foam inhibition are encountered therein. Improved lubricating oil compositions prepared in accord ance with this invention will generally comprise a major proportion of a lubricating oil, generally a mineral lubricating oil, and a minor proportion, 0.1 to 10% by weight, preferably about 0.5 to 5% by weight, base d on the total composition, of the treated detergent additive of this invention.

What is claimed is:

1. The process of substantially reducing the foampromoting tendency in a lubricating oil composition of an oil-soluble detergent additive selected from the group consisting of metal sulfonates, metal alkyl phenol sulfides, phosphosulfurized metal alkyl phenol sulfides and mixtures thereof, which comprises adding about 0.1 to 50% by weight, based on the additive, of an aliphatic alcohol of the C1 to C5 range to an oil solution containing said additive and blowing said oil solution with an inert gas at an elevated temperature until essentially all of said alcohol is removed therefrom.

2. The process of substantially reducing the foam promoting tendency in a mineral lubricating oil composition of a detergent additive selected from the group consisting of metal sulfonates, metal alkyl phenol sulfides, phosphosulfurized metal alkyl phenol sulfides and mixtures thereof which comprises adding about 1 to 30% by weight, based on the additive, of an aliphatic alcohol of the C1 to C5 range to a mineral oil-additive concen trate containing about 10 to 70% by weight of said additive and blowing said concentrate with nitrogen at a temperature of about to C. until essentially all of said alcohol evaporates therefrom.

3. Process according to claim 2 wherein said alcohol is methyl alcohol.

4. Process according to claim 2 wherein said alcohol is ethyl alcohol.

is isopropyl alcohol.

6. Process according to claim 2 wherein said alcohol is N-butanol.

7. An oil-soluble additive which has been rendered substantially non-foaming by the process of claim 1.

8. An additive concentrate containing about 10 to 70% by weight of a detergent additive which has been rendered substantially non-foaming by the process of claim 2.

9. An oil composition of reduced foaming tendencies comprising a major proportion of an organic oil of viscosity at least as high as kerosene and a minor proportion of a normally foam-promoting detergent additive selected from the group consisting of metal sulfonates, metal alkyl phenol sulfides, phosphosulfurized .metal alkyl phenol sulfides and mixtures thereof which has position, of diamyl diethoxysilane.

12. A lubricating oil composition of reduced foaming tendencies comprising a major proportion of a mineral lubricating oil and about 0.1 to 10% by weight, based on the total composition, of a detergent additive which has been rendered substantially non-foaming by the process ofclaim f a Q 1 "13. Composition"according-t0 claim 12 to which-is added 0001 to 1% by weight, based on the total corn- 5 position, of'diamyldiethoxysilane.

References Cited in the file of this patent UNITED STATES PATENTS Borsoif etalia Nov. 18, 1947 Smith Feb.22, 195s 

1. THE PROCESS OF SUBSTANTIALLY REDUCING THE FOAMPROMOTING TENDENCY IN A LUBRICATING OIL COMPOSITION OF AN OIL-SOLUBLE DETERGENT ADDITIVE SELECTED FROM THE GROUP CONSISTING OF METAL SULFONATES, METAL ALKYL PHENOL SULFIDES, PHOSPHOSULFURIZED METAL ALKY PHENOL SULFIDES AND MIXTURES THEREOF, WHICH COMPRISES ADDING ABOUT 0.1 TO 50% BY WEIGHT, BASED ON THE ADDITIVE, OF AN ALIPHATED ALCOHOL OF THE C1 TO C5 RANGE TO AN OIL SOLUTION CONTAINING SAID ADDITIVE AND BLOWING ACID OIL SOLUTION WITH AN INERT GAS AT AN ELEVATED TEMPERATURE UNTIL ESSENTIALLY ALL OF SAID ALCOHOL IS REMOVED THEREFROM. 